What is foundation underpinning and when do NB homes need it?

Foundation underpinning is the process of extending or strengthening an existing foundation so it bears on deeper, more stable soil — it is the primary structural solution when a foundation is sinking, settling unevenly, or needs to be deepened to create more headroom in a basement. In New Brunswick, foundation underpinning is most commonly needed in older homes in Moncton, Saint John, Fredericton, and river valley communities where soil conditions, age-related deterioration, and the relentless effects of NB's freeze-thaw cycles have compromised the original foundation.

When NB homes typically need underpinning:

Settlement and soil failure. If the soil beneath the original footings was inadequately bearing the load — either due to soft clay, organic material, poorly compacted fill, or erosion from water — the foundation will settle and crack. This is common in older NB neighbourhoods where homes were built with minimal site investigation, or on lots that were previously low-lying or filled ground.

Adding a basement or increasing basement height. Many older NB homes were built on shallow crawl spaces or partial basements. Underpinning allows the excavation to go deeper beneath the existing foundation, effectively creating a full basement. This is a complex, expensive project that must be executed in staged sections so the house is never left without adequate support.

Adjacent excavation damage. Construction of a neighbouring building, road work, or utility installation can disturb the soil supporting your foundation, causing settlement. This is more common in dense urban areas of Moncton, Saint John, and Fredericton.

The two main underpinning methods used in NB:

Mass concrete underpinning (traditional pit method) involves excavating in small alternating sections beneath the existing footing and pouring new concrete piers that extend to deeper, stable soil. Each section is completed and cured before the adjacent section is excavated. This is the most common method for residential deepening projects.

Push pier or helical pier underpinning drives steel piers through the existing footing to bedrock or firm bearing strata. Jacks then transfer the building load to the piers and may lift the settled foundation to its original elevation. This is faster and less disruptive than mass concrete underpinning and is well-suited to NB homes with soft soil conditions.

Cost in NB: Foundation underpinning for a typical residential project ranges from $10,000-$25,000 for settlement repair with piers, and $25,000-$60,000 or more for full basement lowering projects. These are major structural projects that require building permits, structural engineering drawings, and experienced contractors. New Brunswick Concrete can connect you with foundation specialists who handle underpinning across NB.